I only use stud.io as well, and have uploaded all my official sets to the ldraw Original Model Repository (OMR) for the past few years. I convert them to LDraw before uploading, but if I remember correctly, one can now also upload them directly as .io files. LDraw Official Model Forum
Although I use studio, the LDraw OMR is my main source for official models as they are also made to a certain standard (Official Repository Standard), and members are very helpful in pointing out mistakes and correcting them. Generally, there is no issue importing the Ldraw files to Stud.io, as long as all the parts are available in the stud.io parts database. If not, one just needs to copy the missing parts across to the Studio custom parts folder.
The forum is very active and includes B-Models and Alternate Models. In addition, as one needs to make a note of which parts or stickers are missing for each upload, there is a good chance that someone see that and will make them for you. There is also a dedicated request thread for parts.
There is also the LDraw OMR database which currently has more than 1800 models OMR Database, but it has not been updated in a while. The forum is the best bet, especially for recent sets.